for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> ENGINEERING (Total: 2118 journals)
    - CHEMICAL ENGINEERING (179 journals)
    - CIVIL ENGINEERING (159 journals)
    - ELECTRICAL ENGINEERING (89 journals)
    - ENGINEERING (1163 journals)
    - ENGINEERING MECHANICS AND MATERIALS (341 journals)
    - HYDRAULIC ENGINEERING (54 journals)
    - INDUSTRIAL ENGINEERING (54 journals)
    - MECHANICAL ENGINEERING (79 journals)

CHEMICAL ENGINEERING (179 journals)                  1 2     

AATCC Journal of Research     Full-text available via subscription   (Followers: 1)
ACS Combinatorial Science     Full-text available via subscription   (Followers: 9)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 4)
Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Advanced Chemical Engineering Research     Open Access   (Followers: 9)
Advanced Powder Technology     Hybrid Journal   (Followers: 13)
Advances in Applied Ceramics     Partially Free   (Followers: 3)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 17)
Advances in Chemical Engineering and Science     Open Access   (Followers: 23)
Advances in Polymer Technology     Hybrid Journal   (Followers: 11)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 5)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 11)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 9)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 6)
BMC Chemical Biology     Open Access   (Followers: 4)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 2)
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Catalysts     Open Access   (Followers: 7)
Chemical and Engineering News     Free   (Followers: 4)
Chemical and Materials Engineering     Open Access   (Followers: 1)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 9)
Chemical and Process Engineering     Open Access   (Followers: 3)
Chemical and Process Engineering Research     Open Access   (Followers: 5)
Chemical Communications     Full-text available via subscription   (Followers: 31)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 24)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 10)
Chemical Engineering and Science     Open Access   (Followers: 3)
Chemical Engineering Communications     Hybrid Journal   (Followers: 10)
Chemical Engineering Journal     Hybrid Journal   (Followers: 20)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 18)
Chemical Engineering Research Bulletin     Open Access  
Chemical Engineering Science     Hybrid Journal   (Followers: 13)
Chemical Geology     Hybrid Journal   (Followers: 12)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Full-text available via subscription   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 362)
Chemical Society Reviews     Full-text available via subscription   (Followers: 32)
Chemical Technology     Open Access   (Followers: 5)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 257)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 6)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 2)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 7)
CORROSION     Full-text available via subscription   (Followers: 2)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 22)
Corrosion Reviews     Full-text available via subscription   (Followers: 4)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 3)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
Ekologia : The Journal of Institute of Landscape Ecology of Slovak Academy of Sciences     Open Access  
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription  
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Fluorescent Materials     Open Access  
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Geochemistry International     Hybrid Journal  
Handbook of Powder Technology     Full-text available via subscription   (Followers: 3)
Heat Exchangers     Open Access   (Followers: 1)
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 20)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
Info Chimie Magazine     Full-text available via subscription   (Followers: 2)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 2)
International Journal of Chemical Engineering     Open Access   (Followers: 7)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 4)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 3)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 3)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 5)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 2)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 4)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 12)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 227)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 8)
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 10)

        1 2     

Journal Cover   Chemical Engineering Science
  [SJR: 1.178]   [H-I: 114]   [15 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0009-2509
   Published by Elsevier Homepage  [2586 journals]
  • Characterization of pore coking in catalyst for thermal down-hole
           upgrading of heavy oil
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Paul Dim , Abarasi Hart , Joseph Wood , Bill Macnaughtan , Sean P. Rigby
      Heavy oil and bitumen are a potential alternative energy source to conventional light crude. However, recovery of these resources can have substantial environmental impact. Downhole upgrading offers the prospect of both improving recovery, and decreasing environmental impact. However, use of catalysts to enhance downhole upgrading is limited by the need for one that can survive the extreme coking conditions arising from the cracking of heavy oil. In this work the potential of hydrogen donors to improve upgrading and enhance catalyst lifetime was considered. In order to extract detailed information on the catalyst structural evolution during reaction a novel parallel adsorption and thermoporometry characterization method was used. This technique allows detailed information to be obtained on the spatial juxtaposition of different pores, and their relative connectivity, as well as on size distributions. For catalyst operated at the conditions studied, it has been found that coking arises in smaller pores branching off the larger pores providing access to the catalyst interior. It has been found that while coking following use of different types of hydrogen donor leads to similar primary patterns of evolution in the pore-scale descriptors of the remaining accessible void-space, differences do arise in the overall accessible volume. Hence, it seems the hydrogen donor affects the location rather than general nature of the pore structure changes. However, at a secondary level of scrutiny, some differences in pore-scale evolution are also identified for different hydrogen donors. These differences identified helped the understanding of variations in the performance of different hydrogen donor and catalyst combinations.
      Graphical abstract image

      PubDate: 2015-04-22T13:14:51Z
       
  • A comparative study and a mechanistic picture of resuspension of large
           particles from rough and smooth surfaces in vortex-like fluid flows
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Ron Shnapp , Alex Liberzon
      Resuspension of freely moving solid particles by a vortex-like flow from surfaces of different roughness is studied using a three-dimensional particle tracking velocimetry (3D-PTV) method. By utilizing the three-dimensional information on particle positions, velocities and accelerations before, during and after the lift-off events, we demonstrate that the resuspension efficiency of the larger than the roughness spherical particles is significantly higher from the rough surface as compared to the smooth surface. The results indicate that for all Reynolds numbers tested, the resuspension rate, as well as the particle velocities and accelerations, is higher over the rough surface, as compared to the smooth counterpart. A mechanistic picture that explains this peculiar effect is proposed. The results can help us to analyze the resuspension rates in engineering and environmental applications of similar flow cases and to improve the specific type of dynamic resuspension models.


      PubDate: 2015-04-22T13:14:51Z
       
  • Simulation of liquid mixing inside micro-droplets by a lattice Boltzmann
           method
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Shufang Zhao , Antoine Riaud , Guangsheng Luo , Yong Jin , Yi Cheng
      We investigated the fundamental aspects of liquid mixing process inside micro-droplets using a recently developed numerical model (Riaud et al., 2014. Phys. Rev. E 89, 053308). Specifically, a two-phase color-gradient model was applied to simulate the generation of droplets in microchannels, while passive tracers only soluble in the dispersed phase were added into the model to characterize the mixing of the solutes without influence on the macroscopic flow field. After introducing the dilute species redistribution scheme and its implementation, the model was validated extensively. We used this numerical method to study the internal mixing of droplets and slugs moving in microchannels. Some of the major influencing factors such as the moving velocity, shape and dimensions of the micro-droplets were tuned to get a comprehensive characterization of the mixing behavior. Depending on flowing time, two successive mixing mechanisms in plugs/droplets moving in a straight channel were disclosed. Firstly there is a fast unsteady convection-dominated stage, at which the mass transfer in the slugs/droplets is controlled by the recirculation motion. However, it turns out to have some stagnant points where convection is inefficient in moving slugs and droplets. The second mixing mechanism is a slower molecular diffusion. At this stage, the solute gradually escapes from the stagnant regions of the droplet and improves the mixing. We further demonstrated that the slow liquid mixing in the latter stage could be spared by adding baffles in the channel to arbitrarily manipulate the two independent circulation zones so as to avoid the existence of the stagnation points in droplets/slugs.


      PubDate: 2015-04-22T13:14:51Z
       
  • Validated a priori calculation of tortuosity in porous materials including
           sandstone and limestone
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Giuliano M. Laudone , Christopher M. Gribble , Katie L. Jones , Hannah J. Collier , G. Peter Matthews
      An algorithm has been developed for the a priori calculation of tortuosity in a simulated void network, assuming a Markovian random walk process, with paths identified using the algorithms of Yen and Dijkstra, and path searching extended by successive pruning of the network graph. The void network is derived from the inverse modelling of percolation characteristics derived from mercury intrusion porosimetry. Experimental tortuosities have been determined for two porous limestones and one porous sandstone, by measuring the electric conductivity of inter-pore brine relative to that of the same quantity of bulk brine. A close match between simulation and experiment is obtained (R 2=0.95). Tortuosities are also calculated for larger charged particles and for viscous transport. Further validation is provided in the form of a sensitivity analysis of tortuosity with respect to network connectivity. The new approach is particularly useful for the many materials that can be characterised by mercury porosimetry or porometry, but for which tortuosity cannot be measured directly. It has applications in a wide range of areas of current interest, such as oil and gas engineering, nuclear reactor core modelling, filtration, catalysis, ceramics, membranes and soil science.


      PubDate: 2015-04-22T13:14:51Z
       
  • Scale-Adaptive Simulation of a square cross-sectional bubble column
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): T. Ma , D. Lucas , T. Ziegenhein , J. Fröhlich , N.G. Deen
      This paper presents detailed Euler–Euler Scale-Adaptive Simulations of the dispersed bubbly flow in a square cross-sectioned bubble column. The main objective is to investigate the potential of this approach for the prediction of bubbly flows with anisotropic liquid velocity fluctuations. The set of physical models describing the momentum exchange between the phases was chosen according to previous experiences of the authors. Experimental data and Euler–Euler Large Eddy Simulation are used for comparison. It was found that the presented combination of sub-models provides good agreement with experimental data for the mean flow and liquid velocity fluctuations. The energy spectra of the resolved velocity obtained from the simulations are presented and compared to the experimental spectra.


      PubDate: 2015-04-22T13:14:51Z
       
  • Engineering batch and pulse refolding with transition of aggregation
           kinetics: An investigation using green fluorescent protein (GFP)
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Siqi Pan , Nora Odabas , Bernhard Sissolak , Moritz Imendörffer , Monika Zelger , Alois Jungbauer , Rainer Hahn
      Pulse refolding is a strategy to overcome concentration dependent aggregation, assuming that aggregation is significantly suppressed under diluted conditions. When a typical 2nd or higher order aggregation kinetics is assumed, kinetics over predicted yields at low refolding concentrations. Using GFP as our model protein, we found a transition in aggregation kinetics from 2nd to 1st order when intermediates deplete from 100 to 60µg/ml. Taking this transition into account, the model can better predict refolding yields in batch and pulse refolding strategies. This model is suited for the design of refolding processes since this deviation from 2nd or higher order aggregation was also previously observed in other proteins.


      PubDate: 2015-04-16T06:28:29Z
       
  • Application of design of experiments in hemodialysis: Optimal sampling
           protocol for β2-microglobulin kinetic model
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Vaibhav Maheshwari , Gade Pandu Rangaiah , Titus Lau , Lakshminarayanan Samavedham
      Toxin kinetic modeling (TKM) for hemodialysis patients is an established method to understand the physiological distribution of toxins, their accumulation, and removal characteristics. To estimate unknown parameters in TKMs, patient blood samples are collected during and after dialysis. The question is—when and how many samples should be collected? Among existing clinical studies, there is no definite consensus on this issue. We employed the model-based design of experiments technique to elucidate the optimal sampling protocol. As the name suggests, its pre-requisite is a model—we considered the diffusion-adjusted regional blood flow model for β2-microglobulin. This model comprises three parameters. A total of 12 scenarios corresponding to 3 experiment durations (240, 300, or 360min)×4 sampling regimes (7, 9, 11, or 13 samples) are simulated, where 240min correspond to conventional dialysis duration. For each scenario, the optimal experiment is designed; parameters are estimated, and compared with known true parameters. The 300min experiment (i.e. 60min post-dialytic wait) with 11 samples is considered optimum among all optimal experiments owing to comparable point estimates, fewer samples, and shorter waiting time after dialysis. Contrary to existing sampling protocols in literature, parameters are better estimated using samples collected in the intra-dialytic phase. The samples in the post-dialytic phase are less informative, and should be collected only towards the end of the post-dialytic phase.


      PubDate: 2015-04-16T06:28:29Z
       
  • A new model for the drag coefficient of a swarm of condensing
           vapour–liquid bubbles in a third immiscible liquid phase
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Hameed B. Mahood , Alasdair N. Campbell , Rex B. Thorpe , Adel O. Sharif
      A semi-analytical model for the drag coefficient of a swarm of two-phase bubbles, condensing in direct contact with an immiscible sub-cooled liquid, has been developed. The analysis used a cellular model configuration, assuming potential (but not inviscid) flow around the reference two-phase bubble in the cell. The effect of the condensation ratio within the two-phase bubbles was included using an approximate relation. The drag coefficient for a wide range of Reynolds numbers ( 0.1 ≤ Re ≤ 1000 ) has been found using the viscous dissipation integral method, and the effect of the liquid content within the two-phase bubble or the half opening angle ( β ) , and the system void fraction ( α ) were examined. The drag coefficient has been found to increase with the condensation ratio and with the void fraction of the system. The present model agrees well with previously available experimental data and theoretical predictions for single bubbles or particles.


      PubDate: 2015-04-16T06:28:29Z
       
  • A comparative study on optical techniques for the estimation of granular
           flow velocities
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Thomas Hagemeier , Matthias Börner , Andreas Bück , Evangelos Tsotsas
      The evaluation of particle velocities in fluidized beds has improved the understanding of ongoing micro- and macro-processes significantly. Several measurement techniques are available in order to estimate single particle velocities as well as granular flow velocities in terms of velocity fields. All of those techniques feature individual advantages and shortcomings, which have been reviewed at various occasions, in particular by Werther (1999) and Horio et al. (2003) or recently by Sutkar et al. (2013). Often, the reviewers presented facility specific findings, which are not to be generalized. Therefore, our study focuses on the comparison of four different measurement techniques, namely fiber optical probe (FOP), laser Doppler velocimetry (LDV), particle image velocimetry (PIV) and particle tracking velocimetry (PTV), which have been applied under identical conditions at one and the same flat fluidized bed facility. Consequently, results obtained with the different techniques feature identical system characteristics and can be compared to derive general conclusions.
      Graphical abstract image Highlights

      PubDate: 2015-04-16T06:28:29Z
       
  • Comparison study of the gas-phase oxidation of alkylbenzenes and
           alkylcyclohexanes
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Olivier Herbinet , Benoit Husson , Hervé Le Gall , Frédérique Battin-Leclerc
      The goal of this paper is to present new experimental results obtained during the study of the gas phase oxidation of ethyl-benzene, n-hexyl-benzene, ethyl-cyclohexane and n-butyl-cyclohexane which belongs to two molecule families present in diesel fuels: alkylbenzenes and alkylcyclohexanes. Experiments were carried out in a jet-stirred reactor over the temperature range 550–1100K. The new results have been compared with existing literature data obtained for alkylbenzenes and alkylcyclohexanes with alkyl chains of different size to highlight the influence of the chain size on the reactivity. The comparison showed that both alkylcyclohexanes exhibit reactivity at both low- and high-temperatures such as cyclohexane and that the reactivity was similar whatever the size of the alkyl chain. For the three compared alkylbenzenes, important differences were observed in the reactivity at low-temperature: ethylbenzene started to react only above 750K, while other compounds reacted from 550K. The comparison also showed that alkylbenzenes were less reactive than their alkylcyclohexane homologs and that the production of aromatic compounds known to promote soot formation was also significantly larger for alkylbenzenes. This paper also presents the effect of the equivalence ratio and pressure on the reaction kinetics. In a general manner, a decrease of the fuel/air ratio significantly increased the reactivity and the carbon monoxide selectivity below 800K, but decreased the selectivity of heavy oxygenated products, the atmospheric degradation of which can be a source of toxic oxygenated products. This decrease had a more limited effect on the reactivity at higher temperatures but disfavored the production of unburned species (oxygenated species like acetaldehyde and unsaturated hydrocarbons which are known to be soot precursors). A pressure increase from 1 to 10bar enhanced the reactivity of all these hydrocarbons over the full studied temperature range, with a start of the reaction at lower temperatures. A larger production of toxic oxygenated products was observed with increasing pressures, while low pressures promoted the formation of soot precursors. Alkylbenzene results were generally well reproduced by simulations using literature models.


      PubDate: 2015-04-16T06:28:29Z
       
  • Bubble breakup in co-current upward flowing liquid using honeycomb
           monolith breaker
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Aly H. Gadallah , Kamran Siddiqui
      Bubble column reactors are used in industrial practices due to their intrinsic advantages of good mixing ability, high heat transfer and operational versatility. Generation of small bubbles in bubble column is a crucial step to improve their performance. The present investigation introduces a new approach for bubble breakup in an upward co-flowing liquid using a honeycomb monolith breaker with square cell structure. The experimental measurements were conducted using high speed imaging at different superficial liquid velocities and gas flow rates ranging between 8 to 50cm/s and 165 to 1000ml/min, respectively. A comparison between the bubbles generated from the monolith breaker and those generated from the nozzle shows that the monolith breaker reduces the bubble size by approximately 60% over the given range of liquid superficial velocities and gas flow rates. It is observed that at low superficial liquid velocities and low gas flow rates, the bubble size at the breaker exit follows log-normal distribution, which becomes more symmetric at higher superficial liquid velocities and gas flow rates. The main contributor of large bubbles formation at the monolith breaker exit is the bubbles׳ coalescence. Different mechanisms of bubbles coalescence at the breaker outlet are observed and classified into three types; multi- and successive “accumulative” coalescence, multi- and non-successive coalescence, and bubbles coalescence in the vicinity of the breaker outlet. The efficiency of the breaker is quantified in terms of the fractional conversion of bubbles׳ kinetic energy into the surface energy. A strong dependency of the breaker efficiency on the superficial liquid velocity is observed. The results indicate that an optimal liquid velocity exists that corresponds to the minimal bubble coalescence at which the breaker efficiency is maximum.


      PubDate: 2015-04-16T06:28:29Z
       
  • Large eddy simulation of a high-pressure homogenizer valve
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Javad Taghinia , Md Mizanur Rahman , Timo Siikonen
      A detailed understanding of the flow behavior inside a high pressure homogenizer (HPH) valve has a vital importance in designing and optimizing the systems in terms of energy and performance. A large Eddy simulation (LES) method is used in this study to investigate the flow structure in an HPH valve. The current paper utilizes two zero-equation subgrid-scale models: namely the RAST (Rahman–Agarwal–Siikonen–Taghinia) and DSM (dynamic Smagorinsky model). The performance of these two models and their predictions are compared with experimental data available in the literature. Computations dictate that an LES can reproduce the accurate information in terms of main parameters that are necessary in designing and optimizing of the homogenizing process. Comparisons demonstrate that both models are capable of predicting the turbulent-flow structures at the gap exit which are in a good agreement with measurements. However, the RAST model shows a slight superiority over the performance of DSM.


      PubDate: 2015-04-16T06:28:29Z
       
  • Screening of ionic liquids for solvent-sensitive extraction –with
           deep desulfurization as an example
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Zhen Song , Teng Zhou , Jianan Zhang , Hongye Cheng , Lifang Chen , Zhiwen Qi
      When applying ionic liquids (ILs) for solvent-sensitive extraction systems, ILs dissolved in the raffinate may lead to severe subsequent problems or a significant reduction in product quality, and thus should be particularly concerned. To screen qualified IL solvent for such systems, a rigorous criterion considering both its solubility in the raffinate and extractive ability is established. The COSMO-RS model is used to evaluate the effect of anions and cations, and suggest potential ILs meeting the criterion. Afterwards, the solubility and extractive ability of candidate ILs are investigated by experiments to further confirm their suitability. The proposed solvent screening method is exemplified for the extractive desulfurization process. [C4mim][H2PO4] is pre-selected by the screening method, and its high extractive performance is experimentally verified.


      PubDate: 2015-04-10T14:42:41Z
       
  • Finite element investigation of the flow and stress patterns in conical
           hopper during discharge
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Q.J. Zheng , A.B. Yu
      Precise evaluation of the dynamics of granular material during hopper discharge, particularly the velocity field coupled with the stress field, has been an important area of research for many years. In this paper, a finite element method (FEM) based on the Eulerian formulation is described and validated to meet this need. It is demonstrated that this method outperforms the ordinary Lagrangian-formulation method in resolving the problem of mesh distortion, thereby is capable of simulating the complete emptying process of a hopper. On this basis, various discharge behaviours of a conical hopper are studied, including the mass and funnel flow modes, the mass flow rate and the wall pressure. The results are in general agreement with those from experiments and recognized correlations in all the examined aspects, which validates the applicability of the Eulerian FEM. This continuum method ought to be of practical significance because it is computationally tractable, and viable in dealing with complex silo geometries and variable flow patterns of granular materials.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • Flux kinetics, limit and critical fluxes for low pressure dead-end
           microfiltration. The case of BSA filtration through a positively charged
           membrane
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Carmen Velasco , JoséIgnacio Calvo , Laura Palacio , Javier Carmona , Pedro Prádanos , Antonio Hernández
      The influence of the applied pressure on the flux decay mechanism during Bovine Serum Albumin (BSA) dead-end microfiltration (MF) has been investigated for a polyethersulfone, positively charged, membrane (SB-6407®) from Pall®. BSA solutions, at pH values of 4, 5 (very close to the protein isoelectric point, IEP) and 6, were micro-filtered through the membrane at different low applied transmembrane pressures. Although filtration was done in dead-end configuration, limit fluxes appeared for all pressures and pH values studied. The concepts of (long time) limit and critical fluxes and their correlation have been clarified and analysed too. The usual blocking filtration laws have been included in a common frame and both the cases with zero or non-zero limit fluxes have been incorporated. Within this frame, the standard model, that assumes an internal pore deposition, has been included as well; although, in our case, the acting mechanism seems to be mainly the so called complete blocking. Protein adsorption has been analysed in terms of the protein–protein and protein–membrane electrostatic interactions. There is a faster flux-decay for the protein isoelectric point with a slightly slower decline in flux when there are both membrane-to-protein and protein–protein repulsion. The slowest kinetics appears for membrane-to-protein attraction with protein–protein repulsion. Moreover, adsorption is stronger, and the limit flux smaller, when the protein is attracted towards the membrane and there is protein–protein repulsion.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • Direct numerical simulation of fluid–particle heat transfer in fixed
           random arrays of non-spherical particles
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): H. Tavassoli , E.A.J.F. Peters , J.A.M. Kuipers
      Direct numerical simulations are conducted to characterize the fluid–particle heat transfer coefficient in fixed random arrays of non-spherical particles. The objective of this study is to examine the applicability of well-known heat transfer correlations, that are proposed for spherical particles, to systems with non-spherical particles. In this study the spherocylinders are used to pack the beds and the non-isothermal flows are simulated by employing the Immersed Boundary Method (IBM). The simulations are performed for different solids volume fractions and particle sizes and low to moderate Reynolds numbers. Using the detailed heat flow pattern, the average heat transfer coefficient is calculated for the different operating conditions. The numerical results show that the heat-transfer correlation of spherical particles can be applied to all test beds of spherocylinders by choosing a proper effective diameter. Our results reveal that the diameter of a spherocylinder is the proper effective diameter for characterizing particle–fluid heat transfer.


      PubDate: 2015-04-10T14:42:41Z
       
  • Coffee stains on paper
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Azadeh Nilghaz , Liyuan Zhang , Wei Shen
      In this study we investigated the underlying mechanisms of coffee stain formation on paper – a porous substrate. When a drop of aqueous liquid containing dispersed materials dries on paper, the faster water evaporation rate at the edge of the drop drives the redistribution of the dispersed materials to the edge of the drop-covered area on paper. Deegan׳s discovery has been accepted as the “coffee ring” phenomenon, which has wide implications. However, stains left by dried aqueous liquids on paper are not always ring-shaped. This is because, besides Deegan׳s coffee ring effect, the transport of dispersed materials in porous media is affected by chromatographic and filtration effects, which are highly dependent upon the properties of the substrates. In this work we clarify the influences of different mechanisms to the dispersed materials redistribution in paper.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • A numerical study on gas–liquid mass transfer in the
           rotor–stator spinning disc reactor
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): K.M.P. van Eeten , R. Verzicco , J. van der Schaaf , G.J.F. van Heijst , J.C. Schouten
      The gas–liquid mass transfer coefficient was investigated in a novel multiphase reactor: the rotor–stator spinning disc reactor. Direct Numerical Simulations of the flow field around a single bubble in the reactor showed that vortex stretching invoked the presence of turbulence inside the thin liquid film surrounding the bubble. The Direct Numerical Simulations further provided a measure for the eddy diffusivity in the thin liquid film caused by this increase in vorticity. An expression was subsequently derived from a mass balance using these eddy diffusivities in order to estimate the order of magnitude of gas–liquid mass transfer coefficients. These estimates were found to lie more in line with experimental results in literature than previously used mass transfer models based on Higbie׳s penetration theory.


      PubDate: 2015-04-10T14:42:41Z
       
  • Influence of ligament shape and thickness on vortex shedding in highly
           porous structures
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Adrian Zenklusen , Stefan Walser , Philipp Rudolf von Rohr
      Highly porous structures (porosity ≥ 75 % ) used as inserts in continuous chemical reactors with characteristic length scale in the millimeter range exhibit at industrial relevant throughputs the transport phenomenon vortex shedding. The dependency of the ligament shape and thickness of the porous media on vortex shedding is investigated in two geometries: a highly porous structure consisting of round ligaments and a highly porous structure whose ligaments are thicker and have a square cross section. The contribution of vortex shedding to the total turbulent kinetic energy is determined from proper orthogonal decompositions (POD) of fluctuating velocity fields measured with particle image velocimetry (PIV). The spatial structure of the vortex shedding phenomenon is addressed by POD eigenfunctions and by the wake length extracted by the position of zero mean streamwise velocity along the wake axis. Shedding frequencies are evaluated for a large Reynolds number range ( 6 ≤ Re D ≤ 1500 ) by a dye injection technique. The vortex shedding phenomenon is more intense in case of the highly porous structure with square and thicker ligaments. This means that larger vortices are created and detached, Strouhal numbers are larger and the contribution of vortex shedding to the total turbulent kinetic energy is more substantial in this case compared with the structure with round and thinner ligaments.


      PubDate: 2015-04-10T14:42:41Z
       
  • Editorial Board
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129




      PubDate: 2015-04-10T14:42:41Z
       
  • Table of Contents
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129




      PubDate: 2015-04-10T14:42:41Z
       
  • Design and optimization of protein refolding with crossflow
           ultrafiltration
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Sylwia Ryś , Renata Muca , Michał Kołodziej , Wojciech Piątkowski , Astrid Dürauer , Alois Jungbauer , Dorota Antos
      This study analyzed the efficiency of protein refolding with crossflow ultrafiltration for two distinct types of model proteins: denatured bovine α-lactalbumin and a fusion protein that comprised green fluorescent protein coupled with an engineered Npro autoprotease tag. A mechanistic model of the process dynamics that accounted for the refolding kinetics was developed and verified by comparing with experimental data. The model was used to quantify refolding performance under various operating conditions, including different denaturant removal rates, refolding durations, and protein concentrations. The performance of ultrafiltration with the fed-batch and stepwise operating modes for denaturant removal was analyzed and compared to the performance of the batch dilution method. Performance was evaluated in terms of productivity, yield, and buffer consumption. The superiority of one refolding method over another depended on the protein system. When a slow reduction in denaturant concentration suppressed protein aggregation, the best performance was achieved with the ultrafiltration system. For example, α-lactalbumin refolding with ultrafiltration achieved several-fold higher productivity and lower buffer consumption compared to refolding with the batch dilution method. A further reduction in buffer consumption was achieved with permeate recycling. Conversely, when rapid dilution of the denaturant was most efficient, a combination of batch dilution and ultrafiltration was recommended. The latter reduced the buffer consumption with permeate recycling; e.g., over 80% of the refolding buffer could be recycled during fusion protein refolding.


      PubDate: 2015-04-10T14:42:41Z
       
  • Droplet–wall interaction upon impingement of heavy hydrocarbon
           droplets on a heated wall
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Amit V. Mahulkar , Guy B. Marin , Geraldine J. Heynderickx
      Regime maps that predict the heavy hydrocarbon droplet impingement behavior on a heated wall (Weber number of the impinging droplet v/s wall temperature) are constructed based on CFD simulations using the Volume of Fluid model with the geo-reconstruct scheme. Based on the simulation results, maps are constructed for single-component droplets with a diameter of 50 and of 100µm. The applied CFD model is validated by comparing these with regime maps available in literature, constructed based on experimental data for model liquids and liquid mixtures. The impingement regimes of Splash, Stick, Rebound and Breakup are well-predicted. Two distinct types of Splash (Splash with ligament formation and Splash with ring detachment) are reported for the first time. Using the validated CFD model, regime maps are constructed for multi-component heavy hydrocarbon droplets with a diameter of 50 and of 100µm. Significant differences between the single-component and the multi-component droplet impact behavior are observed. Improved and new correlations for regime transitions, droplet stretching on the wall, droplet rebounding velocity and number of splashed droplets are derived based on energy balances. They are found to correlate well with CFD predictions.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • Multiscale analysis and modelling of fluid flow within a photocatalytic
           textile
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Robin Degrave , José Moreau , Arnaud Cockx , Philippe Schmitz
      This paper deals with a multiscale strategy for the design of an original reactor that will be an assembly of light photocatalytic textiles. This process is intended to decontaminate industrial effluents such as water containing pesticides. The reactor comprises a fabric and optical fibres and the performance of such a complex textile has to be carefully analysed in terms of fluid flow and the resulting ability to degrade target pollutants. We present an experimental set-up based on classical 1D flow experiments to obtain data on fluid flow through the photocatalytic textile. We also propose a numerical model at the optical fibre scale using COMSOL Multiphysics to perform numerical simulations in a geometrical domain consisting of a Representative Volume Element (RVE) of the photocatalytic textile with periodic boundary conditions. A good fit is found between the permeability of the fabric given by the numerical model and that obtained from experimental measurements, which is also in agreement with the value calculated from an experimental determination of the fabric porosity using a permeability model for fibrous media. Then, the effect of geometrical parameters on fluid flow distribution in the textile is characterized numerically. A short optical fibre pitch maximizes the amount of fluid circulating per unit time in the neighbourhood of the region where the degradation reaction takes place. Finally, a simplified analytical model based on a combination of hydraulic resistances in series and in parallel is implemented and validated with the numerical model mentioned above. This simplified model can be advantageously used for further simulations at industrial reactor scale. Additional simulations on the whole textile are performed to better understand the edge effect currently encountered in 1D flow experiments, which could degrade experimental data. It is found that the edge effect can be neglected in the present experiments.


      PubDate: 2015-04-10T14:42:41Z
       
  • Demulsifying water-in-oil emulsions by ethyl cellulose demulsifiers
           studied using focused beam reflectance measurement
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Zhuqi Chen , Junxia Peng , Lingling Ge , Zhenghe Xu
      Removal of residual water droplets from produced fluids of petroleum is a challenging task because the emulsified water droplets with size of a few micrometers are extremely stable. A focused beam reflectance measurement (FBRM) was used for on-line monitoring of emulsified water droplet size distribution in petroleum emulsion systems and chemical demulsification process. After establishing the feasibility of using FBRM to measure droplet size distributions in petroleum emulsions, factors influencing the average size of water droplets were investigated to evaluate the demulsification dynamics by ethyl cellulose demulsifiers. The FBRM is proven to be a valuable tool for monitoring demulsification process in situ in real time to understand demulsification mechanisms, which sheds the lights on improving the current technology of demulsifying water-in-oil emulsions of petroleum industry.


      PubDate: 2015-04-10T14:42:41Z
       
  • DGLSM based study of temporal instability and formation of satellite drop
           in a capillary jet breakup
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Absar M. Lakdawala , Rochish Thaokar , Atul Sharma
      Temporal instability of a cylindrical capillary jet is analyzed numerically for different liquid Reynolds numbers ( Re = 1 , 10 , 100 ) ,disturbance wave numbers ( 0 < k ≤ 1 ) , and ratio of viscosity of continuous and dispersed phase ( η = 0.01 , 0.1 , 1 ) . Simulations are done using an in-house code based on dual grid Level Set Method. Properties as well as physical interpretations of level set functions are used for characterization of temporal evolution and breakup of a liquid jet, the growth rate of disturbance, the breakup time and its location, and the diameter of primary as well as satellite drop. An excellent agreement of the numerical results with the published analytical as well as experimental results is presented. For higher viscosity ratio system ( η = 1 ) , satellite drops are generated owing to multiple breakup sequences around the neck region of a highly deformed ligament. The breakup mechanism is self-repeating in the sense that every pinch off is always associated with the formation of a neck, the neck undergoes pinch off, and the process repeats. With increasing Re, for all the values of wave numbers, it is found that the growth rate increases; whereas, breakup time decreases. With an increase in the viscosity ratio, the growth rate decreases and breakup time increases accompanied by marginal change in the drop size. Contribution of the total volume of the jet to the satellite (primary) drop decreases (increases) with increasing k, decreasing Re and decreasing η. The present work leads to a better understanding of mechanism of capillary jet breakup and subsequent formation of main, satellite and sub-satellite drops, due to temporal growth of surface perturbation.


      PubDate: 2015-04-10T14:42:41Z
       
  • On the effect of liquid viscosity on interfacial structures within churn
           flow: Experimental study using wire mesh sensor
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Mazdak Parsi , Ronald E. Vieira , Carlos F. Torres , Netaji R. Kesana , Brenton S. McLaury , Siamack A. Shirazi , Eckhard Schleicher , Uwe Hampel
      In the churn flow regime, periodical interfacial structures such as liquid slugs and huge waves can coexist and undoubtedly, a phase property such as liquid viscosity can dominate the behavior of these structures. Regrettably, neither are the characteristics of churn flow widely understood nor have the effects of liquid viscosity on gas–liquid flow received enough attention. A Wire Mesh Sensor (WMS) with a 16×16 spatial resolution was employed to discover the effects of liquid viscosity on the behavior of churn flow in a vertical 76.2mm pipe. Three liquid viscosities of 1, 10, and 40cP, and superficial liquid velocities of 0.46, 0.61, and 0.76m/s were employed; whereas, superficial gas velocity ranged from 10 to 27m/s. Different techniques such as Probability Density Function (PDF), and 2-D and 3-D image reconstruction methods were applied to study the flow. It was noticed that increasing liquid viscosity not only affected the flow pattern but also the appearance frequencies of interfacial structures.


      PubDate: 2015-04-10T14:42:41Z
       
  • Sub-100nm drug particle suspensions prepared via wet milling with low bead
           contamination through novel process intensification
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): M. Li , N. Yaragudi , A. Afolabi , R. Dave , E. Bilgili
      There is sustained interest in sub-100nm particles of poorly water-soluble drugs as such small particles offer improved permeation through various biological barriers and result in rapid onset of therapeutic action. An intensified wet stirred media milling process was developed here for fast production of sub-100nm drug particles with low bead contamination and reduced energy consumption. Griseofulvin and indomethacin, two model poorly water-soluble drugs, were wet-milled. Yttrium-stabilized zirconia beads with a nominal size ranging from 50µm to 800µm were used in the baseline process, which was subsequently intensified with the optimal bead size by increasing rotor tip speed, bead loading, and suspension flow rate stepwise, as guided by a microhydrodynamic model. Laser diffraction, dynamic light scattering, scanning electron microscopy, and XRD were used to characterize the milled suspensions. Results from the baseline process indicated that sub-100nm griseofulvin particles were only produced when 50 or 100µm beads were used in the 360min milling experiments. Interestingly, using 50µm beads led to the formation of sub-100nm griseofulvin particles within 240min with the lowest bead (zirconium) contamination and specific energy consumption. This could be explained though the microhydrodynamic model, revealing that 50µm beads led to the highest frequency of drug particle compressions yet generated the lowest bead contact pressure. The processing time was further reduced to as low as 64min producing griseofulvin particle size of 100nm through step-wise intensification of the milling process with the 50µm beads, as quantified by a milling intensity factor. Due to the enhancement of the breakage kinetics, the process intensification enabled shorter milling to attain 100nm particles, thus resulting in significant energy savings and low bead contamination despite an increase in power consumption. The general applicability of the process intensification method was confirmed through milling of indomethacin, which also led to sub-100nm particles faster with reduced energy consumption and low contamination.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • IR laser induced meniscus evaporation from a microchannel
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Qingyun Xu , Rong Chen , Hong Wang , Xun Zhu , Qiang Liao , Xuefeng He
      In this work, the characteristics of the meniscus evaporation from a microchannel were studied, which was induced by the photothermal effect of the infrared laser with the wavelength of 1550nm. The evaporation rate and mass transfer coefficient at the interface were determined by the proposed image process technique coupled with an infrared camera. Experimental results showed that once the infrared laser was applied, the interface temperature was rapidly increased but with non-uniform distribution as a result of such a tiny local heating source. Accompanying with the rapid temperature rise, the meniscus evaporation was also immediately actuated. After a certain laser heating period, the interface temperature was increased to a stable value with relatively uniform distribution. In the meantime, the evaporation rate increased and became steady. Besides, the effects of the laser power and laser spot position on the evaporation rate and mass transfer coefficient at the interface were also explored. It was shown that both the interface temperature and evaporation rate linearly increased with the laser power as a result of more heat generated. Smaller distance between the laser spot and front interface yielded higher interface temperature and evaporation rate because of smaller heat transfer resistance resulting from smaller transport length. Reducing the distance could make the increase of the evaporation rate to become more significant. With respect to the mass transfer coefficient, it is interesting to find that the mass transfer coefficients under all cases were almost the same, about 0.4m/s.


      PubDate: 2015-04-10T14:42:41Z
       
  • Experimental studies of bubbly flow in a pseudo-2D micro-structured bubble
           column reactor using digital image analysis
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Krushnathej Thiruvalluvan Sujatha , Bennie G.J. Meeusen , J.A.M. Kuipers , Niels G. Deen
      A novel micro-structured bubble column reactor (MSBC) is studied experimentally in this work. Micro-structuring is realized by using a wire mesh inserted in a pseudo-2D bubble column reactor. Different flow configurations of the wire mesh are evaluated by means of visual observation. Three different regimes with bubble cutting, bubble cutting followed by re-coalescence and gas pocket formation were observed for different wire meshes for superficial gas velocities ranging from 5 to 50mm/s. An advanced digital image analysis technique (DIA) was used to determine the effect of wire mesh on the bubble size distribution, gas holdup and interfacial area. Detailed experiments were performed for wire meshes with mesh openings of 3.3mm, 3.7mm and 5.6mm for superficial gas velocities ranging from 5 to 30mm/s. Bubble cutting is observed at 3.7mm mesh opening for superficial gas velocities up to 15mm/s. At higher superficial gas velocities, the bubble breaks up to very small bubbles and bypasses the wire mesh unaffected.
      Graphical abstract image Highlights

      PubDate: 2015-04-10T14:42:41Z
       
  • A reverse nonequilibrium molecular dynamics method for calculating the
           mutual diffusion coefficient for binary fluids
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Hua Yang , Jianguo Zhang , Florian Müller-Plathe , Yongbiao Yang
      This work introduces a nonequilibrium molecular dynamics method for calculating the mutual diffusion coefficient for mixtures. The method is based on the idea of the reverse nonequilibrium molecular dynamics algorithms, and artificially generates a mass flux through the Lennard–Jones mixtures by suitably exchanging particle positions and velocities in different regions. The analysis of the resulting steady-state concentration profiles allows the calculation of the mutual diffusion coefficient. As a test, this method is applied to the calculation of the mutual diffusion coefficient of Ar/Kr systems, and reasonable results are obtained. At the same time, it is observed that the mutual diffusion coefficient strongly depends on the temperature and composition of the mixture. The method can be easily extended to other fluid mixtures and be adopted when studying the nonequilibrium fluid mixtures.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • Investigation of pulsing flow regime transition and pulse characteristics
           in trickle-bed reactor by electrical resistance tomography
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Tong Zhao , Takeshi Eda , Sapkota Achyut , Jun Haruta , Masayuki Nishio , Masahiro Takei
      Electrical resistance tomography was applied to non-invasively visualize the liquid distribution in a lab scale trickle bed reactor. Based on the three-dimensional liquid distribution images (time and two-dimensional space) obtained by the ERT system, effect of the physical properties of the fluids and the packed bed, such as column size, particle diameter, gas density and liquid viscosity, on the pulsing flow regime transition and the liquid pulse structures were clarified. The liquid pulses structures were basically dominated by the small local pulses generated in the capillaries between the packed particles. Promotion of the local pulses generation makes the macro liquid pulses evident and well separated, while restriction of the local pulses generation results in the not fully developed or transient liquid pulses. Moreover, basic hydrodynamic parameters characterizing the pulsing flow, namely the liquid pulse velocity and frequency, were also quantitatively discussed. Liquid pulse velocities were calculated by the cross correlation of the conductivity variations of two ERT sensor with certain distance. The effective liquid pulse frequency which only includes the contribution of the main liquid pulse was determined by identified number of main liquid pulse from the 3D liquid distribution images provided by ERT. The measured liquid pulse velocity and frequency by ERT were then compared with the correlation models proposed in previous literatures.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • A TFM-KTGF jetting fluidized bed coal gasification model and its
           validations with data of a bench-scale gasifier
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Zihong Xia , Youwen Fan , Teng Wang , Xiaofeng Guo , Caixia Chen
      A comprehensive TFM-KTGF simulation was performed with a bench-scale jetting fluidized bed coal gasifier. The numerical results were carefully processed and several key gas–solid hydrodynamic properties, such as the jet height, the bubble size and the amount of solids entrained from the annulus to the jet were validated against literature correlations. The simulated distributions of the bed temperatures, and the gas species compositions (CO, CO2, H2) were validated with reported experiment data (Bi and Kojima, 1996), and compared with those obtained from the TFM-CVM modeling (Gao et al., 2006) as well. It was found that the TFM-KTGF simulation results agreed with the experiment data better than the TFM-CVM, confirming that the TFM-KTGF model could improve the descriptions of gas–solid hydrodynamics of the jetting fluidized bed. The simulation results also showed a high temperature zone in the jet region due to intense char-O2 combustion, whereas the char-H2O, char-CO2 and water gas shift reactions mainly occurred in the annular region, reinforcing the importance of accurately defining and monitoring the jet temperature for an industrial jetting fluidized bed gaisifer.


      PubDate: 2015-04-10T14:42:41Z
       
  • Dispersion in channels of arbitrary cross-sections in presence of active
           surfaces
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Shahin Navardi , Sukalyan Bhattacharya
      This article describes the flow-induced axial dispersion of solutes in conduits of arbitrary cross-sections when the channel wall affects the process due to either adsorption or surface-reaction. The analysis uses a multiple time-scale technique to identify three transport coefficients which characterize the interplays between convection, diffusion and surface-interactions. One of these parameters is well-known diffusion constant recognized in the classical works of Taylor and Aris. In contrast, the other two indicate additional convection and overall slow temporal variation, respectively. Our general formulation obtains these three constants for different commonly seen vessels like the ones with circular, annular, rectangular and elliptical shapes. In case of annular vessels, we consider either inner or outer or both surfaces to be active. Similarly, for rectangle, we repeat the calculations for different numbers of sides involved in the surface interactions. The computed Taylor diffusivity matches with known values for circular and very narrow rectangular conduits. For limiting cases with other geometries, we either derive new exact results or devise novel asymptotic approach based on perturbation analysis yielding useful mathematical expressions for all three transport coefficients. Our computational results are independently verified by these analytical findings when the specific geometric conditions are satisfied.


      PubDate: 2015-04-10T14:42:41Z
       
  • Influence of natural gas production chemicals on scale production in MEG
           regeneration systems
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): A. Yong , E.O. Obanijesu
      Monoethylene glycol (MEG), a common hydrate inhibitor in natural gas transportation pipelines is usually regenerated and reused to minimize operating costs. In this study, three corrosion inhibitors and a scale inhibitor were investigated to understand how production chemicals contribute to scaling (salt loading) at pretreatment and reclamation sections of the regeneration process. The first set of study involved the use of ScaleSoftPitzer software to investigate the possibility of salt deposition at the pretreatment stage. Experiments were then conducted at pretreatment stage for inhibitor doses of 250ppm and 1000ppm. The same sets of experiments were repeated by adding equal concentration of scale inhibitor with each corrosion inhibitor. In the second part of the study, rich MEG recovered from the pretreatment stage was regenerated by reconcentration and vacuum distillation techniques. The solids formed in the liquor were filtered, dried and weighed and the experiments performed at the pretreatment stage repeated. The results showed that level of scaling in the pretreatment stage was well predicted by the software. The experimental results were also consistent with the software predictions. Corrosion inhibitors produced salts that add up to the scaling problems while the scale inhibitor showed more adverse scaling effects comparatively. This is attributed to reduced hydration ability of scale inhibitors compared to corrosion inhibitors that contained smaller functional groups and large alkyl groups. Benzyl dimethyl hexadecylammonium chloride (B.D.H.C) showed higher scale formation ability compared to the other two corrosion inhibitors due to its polarity that influences its affinity for water. Alkalinity was another factor affecting scale formation; the higher the alkalinity, the higher the scale formation. Furthermore, the reclamation stage was found to be highly prone to corrosion and other impacts due to high total dissolved solids (TDS). Besides, a combination of corrosion and scale inhibitors in MEG regeneration system resulted in higher scaling effects compared to the effect of individual inhibitor due to the synergistic interaction between the two inhibitors. The findings of this study show significant implications in large scale continuous operation where salts dissolved in MEG could precipitate to cause scaling, corrosion and gunking amongst others. Escaping less soluble divalent ions are also capable of salting out downstream to cause the same problems within the pipeline and refinery. All these will adversely influence the process safety and the environment.


      PubDate: 2015-04-10T14:42:41Z
       
  • Exergy efficiency of plant photosynthesis
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Cory S. Silva , Warren D. Seider , Noam Lior
      With recent concerns about sustainability and environmental protection, growing attention has been focused on biological sources for both chemicals and fuels; however, to analyze such bioprocesses for commercial viability, and to investigate possible efficiency improvements, the theoretical efficiencies must be known as an upper-bound on performance. Since almost all exergy contained in biomass originates from solar radiation, photosynthesis is the gateway to sustainable bioprocess development. The literature shows a wide range of efficiency predictions, 2.6–41%, due to different definitions and methods of analysis. Therefore, the objective of this study is to dissect the complex bio-processes involved in photosynthesis and analyze the exergy flows through the system, analyzing photosynthesis so as to be understandable by both biologists and thermodynamicists. The initial absorption of light has the lowest exergy efficiency, and it accounts for over 64% of the exergy lost throughout the system. For the light reactions, reduction potentials are used to analyze the flow of excited, high-energy electrons through photosystems II and I, resulting in an exergy efficiency for the light reactions of 32 percent. For the dark reactions, the chemical exergy method proposed by Lems et al. (2007) is appropriate. The resulting efficiency of the dark reactions is 81 percent. Exergy losses to transpiration and photorespiration are taken into account, although their effects are relatively small. The overall exergy efficiency of photosynthesis is calculated to be 3.9 percent. The efficiencies of the sub-processes, as well as the overall efficiency, show good agreement with recent publications. Ultimately, the largest losses are due to poor absorption of light and the inefficient electron transfer through the photosystems.


      PubDate: 2015-04-10T14:42:41Z
       
  • Design consideration in relation to temperature and heat extraction in a
           utility-scale oxy-fuel-fired CFB boiler
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Sadegh Seddighi Khavidak , David Pallarès , Fredrik Normann , Filip Johnsson
      The temperature and heat extraction parameters of a utility-scale, oxy-fuel-fired boiler are investigated using a mathematical model that was originally developed and validated with data from 100-kWth to 4-MWth oxy-fuel-fired circulating fluidized bed units. This work involves an existing furnace, which was developed for air-firing, and evaluates its operational potentials under oxy-fuel conditions, allowing additional heat extraction through an external heat exchanger (EHE). The modeling shows that even though the heat extraction levels from the entire furnace, flue gas pass, and EHE increase with increases in the inlet O2 concentration, the heat extraction from the EHE dominates the heat extraction for high inlet O2 concentrations and, consequently, requires an increase in the circulating solids flow, which transfers heat from the furnace to the seal. While maintaining the same dense bed temperature as in the air-fired case, an increased inlet O2 concentration in the oxy-fired case leads to dramatic increases in the maximum in-furnace temperature and maximum heat extraction flux rate. Thus, to control the maximum furnace temperature, the circulating solids flux must be increased beyond what is required to close the heat balance across the CFB loop. For the conditions investigated, limitation of the maximum furnace temperature to 1273K yields that 48%, 56%, and 70% are the highest possible inlet oxygen concentrations if the external circulation flux rate is limited to 10, 20, and 30kg/m2/s, respectively.


      PubDate: 2015-04-10T14:42:41Z
       
  • Hydrate formation in layers of gas-saturated amorphous ice
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Mars Z. Faizullin , Andrey V. Vinogradov , Vladimir P. Koverda
      Layers of amorphous ice saturated with methane, ethane, propane and carbon dioxide were obtained by condensation of molecular beams of rarefied vapor and gas on a substrate cooled with liquid nitrogen. The amorphous state of such objects at low temperatures is stabilized by the high viscosity and the small value of the stationary nucleation rate of the crystal phase. Their heating in condition of high metastability is accompanied by spontaneous explosive crystallization, which leads to the formation of gas hydrates. Glass-transition and crystallization temperatures were determined by changes in their dielectric properties under heating. An increase in the gas content in layers of amorphous ice causes an increase in the crystallization temperature without any significant changes in the glass transition temperature. At atmospheric pressure in a liquid n-pentane medium the retention of gas hydrates was observed up to temperatures close to 273K. Self-preservation ensured the retention of hydrates in a metastable state at temperatures exceeding considerably their equilibrium dissociation temperatures. Samples of gas hydrates obtained at a maximum gas flow rate during the deposition contained up to 15 mass % of methane, 12 mass % of ethane, 13 mass % of propane, and 23 mass % of carbon dioxide.


      PubDate: 2015-04-10T14:42:41Z
       
  • An experimental analysis of the topology and dynamics of a falling liquid
           film over the wavy surface of a vertical pillow plate
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): M. Piper , C. Wecker , A. Olenberg , J.M. Tran , E.Y. Kenig
      The successful design of pillow-plate condensers requires specific knowledge of the falling liquid film characteristics. Due to the typical wavy, “pillow-like” surface of pillow plates, the film flow here differs from the flow over vertical smooth walls. In this work, we visualized the topology and free surface waviness of a falling liquid film over a vertical pillow plate by using a fluorescent dye and a high speed camera. First observations show that the liquid film preferably flows down the rows of vertically aligned welding spots (zone 1). As a result, the wall surface between these rows is covered by a thinner film (zone 2). In order to quantify this “2-zone” topology, we measured the local mass flow rate in zone 1 over the height of the pillow plate. The results confirmed that the liquid film is mainly “drained” in zone 1. The findings of this study will help to develop flow-pattern-oriented modeling methods and to design pillow-plate falling film equipment.


      PubDate: 2015-04-10T14:42:41Z
       
  • Computational Modeling of bio-MOFs for CO2/CH4 separations
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Ilknur Erucar , Seda Keskin
      Bio-metal organic frameworks (Bio-MOFs), composed of biocompatible metal cations and linker molecules such as amino acids, nucleobases and sugars, are considered as promising candidates for gas storage and separation due to their permanent porosity, chemical functionality and structural tunability. In this study, detailed molecular simulations were performed to assess the potential of 10 different bio-MOFs in adsorption-based and membrane-based separation of CO2/CH4 mixtures. After showing the good agreement between experiments and molecular simulations for single-component adsorption isotherms of several gases in various bio-MOFs, adsorption selectivity and working capacity of these materials were predicted for CO2/CH4 separation. Membrane selectivity and gas permeability of bio-MOFs were computed considering flexibility of the structures in molecular simulations for the first time in the literature. Results showed that several bio-MOFs outperform widely studied MOFs and zeolites both in adsorption-based and membrane-based CO2/CH4 separations. Bio-MOF-1, bio-MOF-11 and bio-MOF-12 were identified as promising adsorbents and membranes for natural gas purification.
      Graphical abstract image

      PubDate: 2015-04-10T14:42:41Z
       
  • Ammonium estimation in an ANAMMOX SBR treating anaerobically digested
           domestic wastewater
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Marisela Vega De Lille , Vera Berkhout , Laura Fröba , Frauke Groß , Antonio Delgado
      Artificial neural networks (ANNs) were used to estimate from online pH-measurements the ammonium concentration in an anaerobic ammonium oxidation (ANAMMOX) sequencing batch reactor (SBR) treating reject water (RW) from the anaerobic treatment of domestic wastewater. The SBR was initially fed with a synthetic autotrophic medium (SM) to assure a stable and ANAMMOX dominating process. After the SBR had been operating stable for 1 month, the removal efficiencies of ammonium and nitrite were equal to 91.22±3.92% and 94.16±8.76%, respectively. The experimental data obtained in this period was taken as basis but not used directly for the training of the ANNs. Instead, the data was used for the calibration of an ordinary differential equations (ODE) model implemented to simulate the nitrogen removal processes that took place in the SBR. This action helped to increase the amount of available data, thereby improving the learning capacity of the networks and reducing the need of extensive experimental analysis. After parameter calibration, the experimental data agreed well with the simulation results in the case of ammonium and nitrite. The simulated ammonium concentration (broadened data set) was then used as target data for the training of different structures of two types of ANNs: multilayer feedforward neural network (MLFNN) and adaptive-network-based fuzzy inference system (ANFIS). The ANNs structures with the best performance after training yielded correlation coefficients (R) of R MLFNN =0.9924 and R ANFIS =0.9922. Afterwards, the selected ANNs were validated by comparing the predicted ammonium concentration with the experimental values obtained during the adaptation from SM to the targeted RW. Both types of ANNs were able to predict with good accuracy the ammonium removal inside the SBR even while dealing with the largely fluctuating influent conditions without the need of further training. The results obtained after validation were R MFLNN =0.8440 and R ANFIS =0.8454. This shows the potential that ANNs have to model the ANAMMOX process if enough and representative data is available for training.
      Graphical abstract image Highlights

      PubDate: 2015-04-10T14:42:41Z
       
  • Product analysis of methane activation using noble gases in a non-thermal
           plasma
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Sungkwon Jo , Dae Hoon Lee , Young-Hoon Song
      As interest grows in methane as a fuel source, its cost-effective activation has become a topic of intensive investigation. As part of these efforts, methane activation using non-thermal plasma was investigated in the presence of various noble gas additives, and the product gases were analyzed. The main products in all cases were alkane species such as C2H6 and C3H8, which were produced independently of the noble gas; however, the conversion of methane was considerably affected by the identity of the noble gas. Because the formation of carbon was a severe problem even in the presence of the noble gases, oxidative methane conversion was also evaluated in terms of the carbon balance and product distribution. By adding oxygen to the methane conversion process, the formation of carbon could be suppressed but the production of higher hydrocarbons was also reduced dramatically. Based on these results, it was concluded that the conversion of methane can be enhanced by varying the discharge characteristics, but the problem of carbon balance must be solved without the addition of oxygen.


      PubDate: 2015-04-10T14:42:41Z
       
  • Impact of continuous particle size distribution width and particle
           sphericity on minimum pickup velocity in gas–solid pneumatic
           conveying
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Aditya Anantharaman , Xin Wu , Kunn Hadinoto , Jia Wei Chew
      The minimum pickup velocity (U pu ) for pneumatic conveying is analogous to the minimum fluidization velocity (U mf ) in fluidization systems in that both dictate the minimum gas velocity required and have important implications in gas–solid flows. However, U pu is not as well-understood as U mf . In this work, the impact of the width of lognormal particle size distributions (PSDs) and particle sphericity (φ) on U pu was determined by the modified weight loss method. Three Geldart Group B materials (namely, glass, aluminum oxide and plastic), with various PSD widths and different particle sphericities (φ), were investigated. Two observations are worth highlighting: (i) as PSD width increases, U pu surprisingly exhibits a non-monotonic behavior (namely, decreases then increases), and (ii) the lower the particle sphericity (φ) is, the greater the extent of the non-monotonic behavior becomes. The discrepancy between the U pu values of the experimental data here and values predicted by available correlations underscores the non-negligible impact of PSD width and particle sphericity, which thereby warrants more understanding and the incorporation of such effects to improve the predictive capability of gas–solid pneumatic conveying.


      PubDate: 2015-04-10T14:42:41Z
       
  • Bioprocess modelling of biohydrogen production by Rhodopseudomonas
           palustris: Model development and effects of operating conditions on
           hydrogen yield and glycerol conversion efficiency
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): D. Zhang , N. Xiao , K.T. Mahbubani , E.A. del Rio-Chanona , N.K.H. Slater , V.S. Vassiliadis
      This research explores the photofermentation of glycerol to hydrogen by Rhodopseudomonas palustris, with the objective to maximise hydrogen production. Two piecewise models are designed to simulate the entire growth phase of R. palustris; a challenge that few dynamic models can accomplish. The parameters in both models were fitted by the present batch experiments through the solution of the underlying optimal control problems by means of stable and accurate discretisation techniques. It was found that an initial glutamate to glycerol ratio of 0.25 was optimal and was independent of the initial biomass concentration. The glycerol conversion efficiency was found to depend on initial biomass concentration and its computational peak is 64.4%. By optimising a 30-day industrially relevant batch process, the hydrogen productivity was improved to be 37.7mLgbiomass−1 h−1 and the glycerol conversion efficiency was maintained at 58%. The models can then be applied as the connection to transfer biohydrogen production from laboratory scale into industrial scale.


      PubDate: 2015-04-10T14:42:41Z
       
  • Analysis of the velocity and displacement of a condensing bubble in a
           liquid solution
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Philip Donnellan , Edmond Byrne , Kevin Cronin
      The absorption of steam bubbles in a hot aqueous solution of Lithium Bromide is a key process that occurs in the absorber vessel of a heat transformer system. During the condensation process, their size and shape changes dynamically with time as they rise up through the column of liquid. An understanding of the factors that control the vertical upwards motion of the bubbles is necessary to enable proper design of such units. However, the exact vertical displacement of a bubble moving through a liquid is difficult to predict and becomes much more complex if the bubble is simultaneously collapsing. In this paper, the displacement of steam bubbles collapsing in a concentrated aqueous lithium bromide solution (LiBr–H2O) has been quantified experimentally. A simple kinetic model predicting the vertical displacement as a function of time was then developed from elementary force–balance considerations. A key feature of the system is the large variability in the motion of the bubbles arising from extreme fluctuations in their size and shape. Bubble dynamic morphology was modelled with stochastic techniques and the output from this was used in the kinetic model to predict dispersion in bubble displacement with time. While the uncertainty predicted by the stochastic model is shown to be less than that observed experimentally, it nonetheless highlights the importance of this random behaviour during the design of such an absorption column.


      PubDate: 2015-04-10T14:42:41Z
       
  • Short-chain branching distribution oriented model development for Borstar
           bimodal polyethylene process and its correlation with product performance
           of slow crack growth
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Zhou Tian , Ke-Ran Chen , Bo-Ping Liu , Na Luo , Wen-Li Du , Feng Qian
      This work aims to develop a model that can predict the short-chain branching distribution (SCBD) of bimodal polyethylene (BPE) for an industrial Borstar process and correlate it with an updated structure–performance model (SPM) to estimate the slow crack growth (SCG) performance of the product. To calculate the SCBD and molecular weight distribution (MWD) simultaneously, a rigorous process model (i.e., kinetic model, thermodynamic model, reactor model) combined with a specific calculation method is established. The predicted SCBD and MWD of BPE are in good agreement with the plant data. An updated SPM that allows the estimation of the SCG resistance of BPE from its molecular architecture is developed, taking the effect of SCBD into account. The SPM reveals that the predicted SCG performance of BPE will be underestimated when only the average SCB content will be considered. The process model is coupled with the updated SPM, and it is capable of a full assessment on the effects of various operating conditions on the SCBD link with the MWD and, in turn, the SCG performance of BPE produced in the Borstar process. The underlying relationships are also discussed.


      PubDate: 2015-04-10T14:42:41Z
       
  • Effect of alcohol frothing agents on the coalescence of bubbles coated
           with hydrophobized silica particles
    • Abstract: Publication date: 28 July 2015
      Source:Chemical Engineering Science, Volume 131
      Author(s): Ghislain Bournival , Ludmila de Oliveira e Souza , Seher Ata , Erica J. Wanless
      The stability of capillary-pinned bubble pairs covered with hydrophobized particles in aqueous solutions of 1-pentanol or methyl isobutyl carbinol (MIBC) was studied using high-speed cinematography. Glass particles were first rendered hydrophobic by covalently bonding a linear alcohol onto the solid interface to achieve a specific hydrophobicity (i.e. contact angle of 43° measured with the captive bubble on a treated wafer) and effectively avoid the presence of any mobile hydrophobizing surfactant. The resistance to coalescence of the bubbles was measured at different frother concentrations and for various initial bubble interfacial areas covered by particles; with particle coverage not exceeding the contact region between the bubbles. Frother molecules were shown to delay the coalescence of bubbles whereas particles were not present in a sufficient quantity at the interface of the bubbles to provide steric stability. However, in some cases in the presence of MIBC, the particles were believed to act as means of transportation for the frother molecules to the surface of the bubbles thus forcing the local relaxation of the interface, which improved bubble stability. The coalescence of two bubbles released energy causing a rapid motion of the interface. This motion was sufficient to expel a fraction of the attached particles from the interface. The addition of frother, and of particles in some cases, increased the dampening of the oscillatory motion generated by bubble coalescence. In general, damped bubble oscillations were associated with a reduced quantity of particles detaching from the bubble. Although particles were observed to dampen the oscillation of the bubble, they were not as effective as the frother molecules in reducing the detachment of particles upon bubble coalescence. This finding is believed be of relevance for industrial applications such as froth flotation.


      PubDate: 2015-04-10T14:42:41Z
       
  • Double emulsion production in glass capillary microfluidic device:
           Parametric investigation of droplet generation behaviour
    • Abstract: Publication date: Available online 20 March 2015
      Source:Chemical Engineering Science
      Author(s): Seyed Ali Nabavi , Goran T. Vladisavljević , Sai Gu , Ekanem E. Ekanem
      A three-phase axisymmetric numerical model based on Volume of Fluid–Continuum Surface Force (VOF–CSF) model was developed to perform parametric analysis of compound droplet production in three-phase glass capillary devices that combine co-flow and countercurrent flow focusing. The model predicted successfully generation of core-shell and multi-cored double emulsion droplets in dripping and jetting (narrowing and widening) regime and was used to investigate the effects of phase flow rates, fluid properties, and geometry on the size, morphology, and production rate of droplets. As the outer fluid flow rate increased, the size of compound droplets was reduced until a dripping-to-jetting transition occurred. By increasing the middle fluid flow rate, the size of compound droplets increased, which led to a widening jetting regime. The jetting was supressed by increasing the orifice size in the collection capillary or increasing the interfacial tension at the outer interface up to 0.06N/m. The experimental and simulation results can be used to encapsulate CO2 solvents within gas-permeable microcapsules.
      Graphical abstract image

      PubDate: 2015-04-01T11:50:15Z
       
  • A systematic investigation of the performance of copper-, cobalt-, iron-,
           manganese- and nickel-based oxygen carriers for chemical looping
           combustion technology through simulation models
    • Abstract: Publication date: 7 July 2015
      Source:Chemical Engineering Science, Volume 130
      Author(s): Sanjay Mukherjee , Prashant Kumar , Aidong Yang , Paul Fennell
      The Integrated Gasification Combined Cycle coupled with chemical looping combustion (IGCC-CLC) is one of the most promising technologies that allow generation of cleaner energy from coal by capturing carbon dioxide (CO2). It is essential to compare and evaluate the performances of various oxygen carriers (OC), used in the CLC system; these are crucial for the success of IGCC-CLC technology. Research on OCs has hitherto been restricted to small laboratory and pilot scale experiments. It is therefore necessary to examine the performance of OCs in large-scale systems with more extensive analysis. This study compares the performance of five different OCs – copper, cobalt, iron, manganese and nickel oxides – for large-scale (350–400MW) IGCC-CLC processes through simulation studies. Further, the effect of three different process configurations: (i) water-cooling, (ii) air-cooling and (iii) air-cooling along with air separation unit (ASU) integration of the CLC air reactor, on the power output of IGCC-CLC processes – are also investigated. The simulation results suggest that iron-based OCs, with 34.3% net electrical efficiency and ~100% CO2 capture rate lead to the most efficient process among all the five studied OCs. A net electrical efficiency penalty of 7.1–8.1% points leads to the IGCC-CLC process being more efficient than amine based post-combustion capture technology and equally efficient to the solvent based pre-combustion capture technology. The net electrical efficiency of the IGCC-CLC process increased by 0.6–2.1% with the use of air-cooling and ASU integration, compared with the water- and air-cooling cases. This work successfully demonstrates a correlation between the reaction enthalpies of different OCs and power output, which suggests that the OCs with higher values of reaction enthalpy for oxidation (ΔH r, oxidation ) with air-cooling are more valuable for the IGCC-CLC.
      Graphical abstract image

      PubDate: 2015-04-01T11:50:15Z
       
  • Evaluation of a structural mechanics model to predict the effect of
           inserts in the bed support of chromatographic columns
    • Abstract: Publication date: 16 June 2015
      Source:Chemical Engineering Science, Volume 129
      Author(s): Spyridon Gerontas , Tian Lan , Martina Micheletti , Nigel J. Titchener-Hooker
      Cell culture titres are expected to increase still further over the forthcoming years. This imposes challenges for downstream processing including the potential need to use larger volumes of chromatography resins. Such a move could create throughput bottlenecks because of the compressible nature of many commercially available resins, which makes the operation of columns with diameters beyond 2m infeasible due to resin collapse. The use of cylindrical inserts of negligible thickness has been proposed in the literature as a way to enhance the level of wall support, allowing higher superficial flow velocities to be applied and hence larger diameter columns to be used. In this study, a structural mechanics model has been developed to evaluate the effect of inserts on the column pressure drop and flow characteristics. Simulations were shown to be in good agreement with published experimental data. The model was then used to predict the effect of insert number, diameter, height and roughness on critical velocity of manufacturing scale columns.


      PubDate: 2015-03-12T23:57:20Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2015